This isn't a NULL pointer dereference; returning &(0->page) is completely legal as was discussed regarding this exact code back in April: https://lore.kernel.org/lkml/YmfgqKcMmstgfz+0@xxxxxxxxxxxxxxxxxxxx/ > On Jul 27, 2022, at 12:46 AM, Yongqiang Liu <liuyongqiang13@xxxxxxxxxx> wrote: > > When __filemap_get_folio() failed and returned NULL, we would > get a NULL pointer dereference in pagecache_get_page. > > Fixes: 3f0c6a07fee6 ("mm/filemap: Add filemap_get_folio") > Signed-off-by: Yongqiang Liu <liuyongqiang13@xxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.16 > --- > mm/folio-compat.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/folio-compat.c b/mm/folio-compat.c > index 20bc15b57d93..7b21393480e0 100644 > --- a/mm/folio-compat.c > +++ b/mm/folio-compat.c > @@ -124,7 +124,9 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, > struct folio *folio; > > folio = __filemap_get_folio(mapping, index, fgp_flags, gfp); > - if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio)) > + if (!folio) > + return NULL; > + if ((fgp_flags & FGP_HEAD) || xa_is_value(folio)) > return &folio->page; > return folio_file_page(folio, index); > } > -- > 2.25.1 > >
